Regular, preventative maintenance of your boat and its systems is critical when undertaking an ocean passage; even more so when you're pushing the boat in race trim. A significant part of your maintenance programme will include your sail wardrobe and standing and running rigging.

To check the rig, blocks and halyards, you're going to need to do a mast ascent and this will mean undertaking a risk assessment. Yes, yes, 'Health and safety', but believe me, the first time you leave the rig in an unplanned swing, you'll be a believer! Climbing a rig when underway is different to when sitting alongside a dock.

In any event, before you start, you should be wearing a lifejacket with safety line, helmet, possibly fingerless leather-palmed sailing gloves (optional) and if you are taking tools with you make sure they are clipped to your harness (so that you don't drop them on your crew mate's head).​Having a sealable bag on your belt is useful for things like insulation tape, spare bulbs, etc and I'd recommend you take a multitool / safety knife (also on a lanyard) and accessible when you are in your harness. Don't do what I once did and put it in your dry suit thigh pocket, then realise you can't get to it when you need it because your climbing harness prevents access to your pocket!

If you plan on being up there a while, a 70 cm long strop with a carabiner clip on both ends can be useful for attaching yourself more securely to the mast whilst working aloft.​Once the climber is ready, check the lines for the climb as follows;

You'll want two halyards, in the very unlikely event that one fails. Also, make sure the halyards run through the mast, not halyards that run completely outside the mast on masthead blocks (Kite halyards are sometimes run outside the mast and should not therefore be used as an ascent line for this reason).

You'll probably want to use halyards from opposite sides of the rig. The reason being that this will allow each halyard a good run to a separate winch. Make sure the primary halyard is running free and clear and isn't twisted or chafing on the rig.

The second halyard (your safety back up) should also be running clear.

Make sure that the climber's end of each halyard runs down the same side of the rig, otherwise you are going to have a problem at the first inner stay's connection to the mast (assuming you have an inner stay of course). This might mean running the safety around the forestay so that both halyards run up the same side of the rig.

Obviously, the safety will be chafing slightly on the top of the forestay, but as it's not going to be under any significant load, this won't matter.

Never trust a shackle with your life; bowlines every time, and tie onto the strong point on your climbing harness or bosun's chair (I prefer the former when at sea) and then clip the shackle (with a little slack in it) onto the climbing harness.

You may need to tie a bowline on the bight to do this. Then tie the second halyard around the climbing harness strong point (and around another part of the harness), clipping the shackle end onto the strong point on your life jacket.

Make sure your life jacket has crotch straps on - and they are fastened!

Make sure you have a method for communicating with the deck. Being 100ft up a mast in a blow is a pretty lonely place and trying to shout over wind noise is going to be difficult. I like having agreed hand signals for 'hold', 'winch / grind', 'ease'. At night, a torch and flash system might be needed (or a radio).

Brief your crew. Make sure you have a trustworthy winch handler on your primary winch at the very least!

Before you start the ascent, you are going to need something to stop you swinging off the mast and acting like a conker, halfway up. There are a lot of hard, sharp bits of metal up there and you get quite a speed up if you do start swinging. Trust me, I know. I'd recommend using your safety line. Clip it to your lifejacket hard point, then put it around a halyard that goes to the top of the mast (on the same side as the ascent) and clip it back to your jacket. This way, you are not 'connected' to the third halyard but, if you lose connection with the mast your swing will be limited to 2 or 3 metres. It'll still hurt, but you'll be under some control.

If you don't have a spare third halyard then rig a downhaul line, attaching it to your harness strong point and running it down to deck, preferably through a block near the mast foot at deck level and back to a winch. This too, will help arrest a swing. On a very large vessel, a downhaul must be used, otherwise, there might come a time where the weight of the halyard in the mast overcomes the weight of the climber and at that point up you go! Not pretty.

On the ascent, if you are fit and strong enough to climb, make sure your crew mates know so that they can take up slack as you go. If you're going to be winched, try and stay on the high side and ascend spiderman like, making sure to keep hold of the mast and rigging as you go. If the boat is heeled over, stay on the windward side of the mast and that way you have gravity working on your side. Watch you don't get fingers and heels stuck in the nooks and crannies of the rigging.

As you go up, someone needs to be running the deck, making sure winches are being handled properly. Someone should also be 'eyes on' the climber at all times, relaying signals as they ascend. Once there, the halyards should be secured and I'd recommend a clove hitch on top of the winch turns at the end, so as to prevent a line coming off a winch or someone accidentally removing the line. On this point, never leave your winch when there is a crew member on the end of the line! Close the clutches on the halyards if you have them.

​On descent, first, open the clutches, then remove the clove hitches. Take the primary winch down to the number of turns that will allow you to ease the climber freely, but under control. This will vary dependent on the halyard and winch size but three turns is probably good. The secondary winch needs to be eased faster than the primary (otherwise it'll be a jerky and uncomfortable descent for the climber). You might consider removing turns to 2 turns and let the line run freely as the primary winch controls descent speed. Don't let the halyards run through your hands. Ease them in long, smooth actions, hand to hand - their crotch area will appreciate it.

As the climber descends, the person in charge keeps watching the climber at all times and communicating with the deck crew. Once back at deck, make sure all halyards are secured properly to the pin rail, making sure that each halyard run is correct and not tangled around the forestay or rig. Always look up when handling halyards to prevent this eventuality.

Despite all of this, it can still go wrong. Just make sure you remain attached to the third halyard or downhaul and a painful swing is the worst you can expect.